Nail polish is generally applied to fingernails or toe nails as two or more layers, for example in the form of a base coat layer, one or more pigmented layers, and a top coat. It is generally desirable for each applied coat to be dry before the application of the next coat. However, such drying time substantially increases the total time required for a multi-coat application. It is also desirable that the last coat dry relatively quickly so that the wearer is free to engage in other activities promptly after completing the application of the last coat. However, if the exterior surface of the top coat dries too fast, solvents can be trapped at the interface between the top coat and the previously applied undercoat, reducing the cohesiveness of the previously applied undercoat and the adherence of the top coat to the previously applied undercoat.
Fuller, U.S. Pat. No. 2,173,755 discloses a nail enamel which spreads easily and dries within one and a half minutes to produce a single layer of a non-tacky, durable film, which is readily removable by ethyl acetate and butyl acetate. The Fuller composition utilized non-explosive esters of cellulose dissolved in organic solvents, e.g. ethyl cellulose or cellulose aceto butyrate dissolved in ethylene dichloride, as a replacement for the previously employed nitrocotton, which is explosive. Fuller used diethylene dioxide as a solvent for resins and plasticizers which were to be added to the cellulose ester/organic solvent mixture.
Rossomando, U.S. Pat. No. 4,179,304, discloses the use of a nail polish composition comprising sucrose acetate isobutyrate, a resin selected from sucrose benzoate and sucrose benzoate with polymeric methyl methacrylate, and a plasticizer selected from organic phthalates, organic adipates and organic phosphates, e.g. butyl benzyl phthalate. An objective of the Rossomando composition was to avoid the use of carcinogenic formaldehyde containing resins which had been previously employed in nail polish compositions. Rossomando also discloses that film forming resins such as nitrocellulose, cellulose propionate, cellulose acetate butyrate, ethyl cellulose and acrylic resins could be blended into his nail polish composition. Rossomando discloses the use of a combination of ethyl acetate, butyl acetate and toluene as the solvents for the isopropyl wet nitrocellulose in the basic composition of his working examples.
Martin et al, U.S. Pat. No. 5,130,125, discloses a nail polish top coat composition for application over wet nail polish which dries quickly to a non-tacky, non-brittle solid coat. The preferred composition is set forth in Example 1 of U.S. Pat. No. 5,130,125 as containing toluene, n-butyl acetate, cellulose acetate butyrate ester 318, cellulose acetate butyrate ester 551, benzophenone-1, butyl benzyl phthalate, polysiloxane copolymer, and isopropyl alcohol. While this Martin et al top coat has many advantages, the use of toluene is considered to be undesirable because it is toxic by ingestion, inhalation, or skin absorption, and may cause mild macrocytic anemia. Accordingly, there is a need for a top nail coat composition which is at least substantially free of aromatic solvents such as toluene.
Also, while the benzophenone-1 in the Martin et al top coat composition is a good UV blocking agent, it does not provide the desired level of UV blocking for the full range of ultraviolet radiation. Accordingly, there is a need for a top nail coat composition which has an enhanced range of UV blockage. Similarly, while the polysiloxane copolymer of the Martin et al composition reduces friction, improves the flow of the top coat composition during application, and improves the levelness and gloss of the surface of the top coat composition upon drying, the adhesion of the top coat to the previously applied coats is not as strong as is desired.